First stage of thermal aging under oxidizing conditions of a Ce0.62Zr0.38O2 mixed oxide with an ordered cationic sublattice:: A chemical, nanostructural, and nanoanalytical study

After being heated in a flow of 5% O-2/He, at 1073 or 1123 K for 30 min, a Ce0.62Zr0.38O2 sample showing an ordered cationic sublattice had very subtle surface nanostructural changes induced on it. In parallel with them, a significant loss of low-temperature (T <= 773 K) oxygen storage capacity (OSC), with no modification of its high-temperature (T >= 973 K) redox response, was observed. These nanostructural and chemical features characterize the very first stage of the process leading to the destruction of the ordered Ce-Zr sublattice, a structural phenomenon playing a key role in the control of redox behavior of ceria-zirconia mixed oxides. The reported results, including OSC, hydrogen chemisorption, and nanostructural and nanoanalytical data, lend further support to a model providing a comprehensive interpretation of the complex relationship linking thermal aging conditions, nanostructural properties, surface chemistry, and redox behavior in these materials.